How to get an Identity column value (not committed yet) inside a transaction

Question

Inside a TSQL transaction I have an operation of inserting a record into a MyTable1 and an operation of updating a MyTable2 with a value of Identity column of the MyTable1 record, which is only to be inserted after the transaction is commited.
So, how to get this autogenerated value before it is actually inserted into the table?

Code just to illustrate the question:

CREATE TABLE MyTable1(
MyTable1Id int identity(1,1) primary key,
Field1 varchar(50)
) 

CREATE TABLE MyTable2(
MyTable2Id int identity(1,1) primary key,
MyTable1Id int
)


CREATE PROCEDURE MyProc(
   @MyVal1  [varchar](50)
)
AS
BEGIN TRAN
-- try to insert
INSERT INTO MyTable1(
   Field1
)
SELECT @MyVal1

IF @@ERROR <> 0
BEGIN
  ROLLBACK TRAN
END

-- update MyTable2
DECLARE @TheUnknownIdValue int
UPDATE MyTable2
SET    MyTable1Id = @TheUnknownIdValue -- how to get the value needed here?
WHERE ...

IF @@ERROR <> 0
BEGIN
  ROLLBACK TRAN
END

COMMIT TRAN 

Answer 1

Use SCOPE_IDENTITY() just after the INSERT

--
DECLARE @newId INT 
INSERT INTO MyTable1(
   Field1
)
SELECT @MyVal1
--End of Insert here
SELECT @newId = SCOPE_IDENTITY()
--Rest of the procedure